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光电导天线的辐射特性仿真是设计和制造光电导天线的重要依据。将蒙特卡洛经验公式修正的GaAs迁移率随电场强度的变化关系引入德鲁德-洛伦兹模型,分析了光电导天线载流子输运情况。又将德鲁德-洛伦兹模型计算的光生载流子密度与时域有限差分方法相结合,得到34μm孔径GaAs偶极子光电导天线的时域、频域及三维辐射特性。辐射峰值为0.8 THz,频谱宽度大于1 THz,与太赫兹时域光谱系统实际测量得到的数据吻合。结果表明:仿真方法正确可行,能够为设计和制造高增益、宽频带的太赫兹光电导天线提供参考依据。
The simulation of the radiation characteristics of photoconductive antennas is an important basis for the design and manufacture of photoconductive antennas. The GaAs mobility modified by Monte-Carlo empirical formula was introduced into the Drude-Lorentz model according to the change of electric field intensity, and the carrier transport of the photoconductive antenna was analyzed. In the meantime, the photo-generated carrier density calculated by the Druid-Lorentz model is combined with the finite difference time-domain method to obtain the time-domain, frequency-domain and three-dimensional radiation characteristics of the 34μm aperture GaAs dipole photoconductive antenna. The radiation peak is 0.8 THz and the spectral width is greater than 1 THz, which is consistent with the actual measured data of terahertz time-domain spectroscopy system. The results show that the simulation method is correct and feasible, which can provide a reference for the design and manufacture of high gain and broadband terahertz photoconductive antenna.